Pectin and its manufacture



Patented Sept. 11, 1934 UNITED STATES PATENT OFFICE PECTIN AND ITS M NUFacTUaE poration' of Delaware No Drawing. Application July 11, 1933, Serial No. 679,853

20 Claims.

This invention relates to pectin and its manufacture and more particularly to the treatment of certain pectin bearing materials to obtain a substantially pure, unadulterated product hav- Eng certain advantageous characteristics which, so far as I am aware, have not hitherto been present in pectin products.

Heret-ofore, pectin extracted from a suitable pectin containing pomace has usually been distributed commercially either in the form of a liquid concentrate or a powder. In neither form has it been. entirely satisfactory. Liquid pectin, or more exactly, pectin dispersed in a liquid which is usually water, is bulky, heavy and cumbersome 15, to handle and deteriorates rapidly upon exposure to the atmosphere and also, to some extent, when stored in sealed containers. Pectin powder, while more resistant to deterioration than the liquid, is very difficult to disperse due to the fact that water causes the particles or grains to swell and stick together, eventually forming large lumps, greatly reducing the surface exposed to the water and slowing up the dispersion of the pectin therein. A peculiarity of the material is that the higher the grade of pectin, that is to say the greater the jellying power of the pectin, the greater the tendency to form lumps and the more difficult it becomes to disperse it uniformly in water. Consequently, commercial pectin pow- 3 der is usually of low effective jellying power.

Efforts have been made to increase the rate of dispersion of powdered pectin by mixing with the pectin some such material as sugar which tends to keep the pectin particles separated and thus prevent lumping during dispersion. Sodium bicarbonate with a small amount of acid has also been mixed with powdered pectin to increase its rate of dispersion by liberating carbon dioxide gas throughout the mass when mixed with 0 ,water and in this way keeping the particles of pectin separated and preventing lumping. However, these methods not only become less effective with pectin of higher grade, but require the addition of an extraneous material to the pectin thus adulterating the subsequent mixture when such pectin is used and in some cases actually lowering the effectiveness or jellying power of the pectin. In any event such efforts are little more 5 than makeshifts and are not satisfactory from a commercial point of view.

An object of this invention is to produce pectin in a readily dispersable, easily handled dry form capable of being kept in an ordinary moisture proof package for prolonged periods of time without serious deterioration by an improved method, and to provide pectin having a desired pH value.

The present invention provides a dry, deterioration-resistant pectin having a physical structure of such form as to prevent lumping when the material is introduced into a suitable liquid vehicle and to expose a relatively large area of pectin surface directly to the liquid so that even the highest grade of pectin will disperse readily without substantial agitation. The physical structure of the pectin is such that the different particles contact with the solvent rather than each other and balling or lumping of the pectin is prevented. I accomplish this, as will hereinafter be more fully described, by producing dry pectin in the form of a very thin film or sheet from liquid pectin, either in'concentrated or unconcentrated form, which is subjected to a drying temperature while spread in an even layer of the proper thickness directly upon an unencumbered drying surface.

Heretofore it has been impossible to remove pure pectin in the form of a sheet or film from a drying surface because it adheres so tenaciously thereto and can only be scraped off with great difiiculty and then only in the form of a powder or of small chips. Such powdered pectin or chips would have no advantages over present commercial powdered pectin. In such a process it is impossible to completely remove the material from thedrying surface when desired at any definite point. Hence the length of time that the ma-- terial is subjected to the drying temperature cannot be accurately controlled and the product may vary throughout and be of uncertain characteristics and jellying power.

Although it has been proposed to provide for the removal of pectin from a drying surface in sheet form by distributing some intervening material, which will not itself adhere to the drying surface, directly thereon and then drying the peetin by spreading it over the intermediate material, such a process is unsatisfactory because whatever material is employed to keep the liquid pectin from contact with the drying surface will adhere to or be dispersed throughout the final pectin sheet and cannot be removed therefrom without destroying the piwsical structure of the sheet. Even if powdered pectin itself is used as an intermediate material the pectin content thereof will be injured by the heat and the finished sheet or film will comprise a heterogeneous mixture of pectin in various physical forms a part of which, the pectin powder, will resist solution as heretofore stated.

I have found that when liquid pectin has a suitable adherence retarding agent incorporated therein and is then spread on a suitable drying surface it may be dried thereon and then easily and completely removed therefrom by a suitable scraper or knife. These agents apparently operate to retard or temporarily minimize the inherent tendency of the pectin to adhere to the drying surface without materially impairing the effectiveness of the pectin in subsequent use. If the drying is accomplished, for example, by spreading the liquid pectin on the outer face of a rotating, interiorly heated cylinder, the dried pectin can be continuously removed in the form of a very thin, continuous sheet or film. Various agents can be used for this purpose for example certain polyhydric alcohols, such as glycerine, and some of their derivatives; certain oils such as olive oil, lemon oil, refined mineral oil or petrolatum,v

suitable waxes; parafiins and sugars. In some instances the natural product from which the peetin is extracted may be so selected, or several products so combined, that a sufficient amount of one or more of these agents will be present, but

in most instances it will be found advantageous to add the proper agent to liquid pectin in the proper proportion.

Some of these agents are readily soluble-in or miscible with the pectin containing liquid, and therefore easily incorporated. Those which are not, such as some of the oils, waxes and paramns may be easily dispersed in' the pectin containing liquid in the form of an emulsion by virtue of the emulsifying power of the pectin. The'waxes, including those of the paraffin series, while solid at ordinary temperatures, may be melted and easily dispersed in the pectin liquid by sufficiently agitating the liquid during the addition of the melted wax.

In carrying out'the present invention a substantially pure liquid pectin is made from pectin containing pomace or the like in any well known manner as by leaching, extracting and clarifying according to known methods or in any other suitable way. Having obtained liquid pectin the extract may be concentrated or not as desired, but a certain amount of concentration is preferable in order to increase the viscosity of the liquid and the ease of handling it on the drying surface. The degree of concentration will depend somewhat upon the grade of pectin present. The higher the grade of pectin the lower the concentration of the solution due to the fact that the viscosity varies directly with the grade of pectin. For example, a 100 grade pectin (that is a pectin one part of which will jell 100 parts of sugar by weight under standard conditions) may be concentrated to a 4% solution and it will be found to have a viscosity that makes the material easy to handle. However, if desired, a 2% solution can be used and the resulting product will be entirely satisfactory. The successful production of dry pectin in accordance with the present method does not depend upon the concentration or viscosity of the original pectin solution as almost any desired degree of concentration can be employed with suitable alterations of the drying apparatus. Assuming that a 4% solution is to be dried, and that glycerine has been selected as the adherence retarding agent, I add approximately 3 gallons of glycerine to each 100 gallons of the solution and agitate the mixture until it is homogeneous. The amount of glycerine is variable and if the pectin concentrate contains any appreciable amount of sugar or natural oil the amount The liquid mixture thus made is fed into direct contact with a smooth, unencumbered, heated drying surface by any suitable feeding apparatus capable of spreading the material over such surface in a thin, substantially even layer. Any suitable type of drying surface can be employed, it only being necessary that such surface be sufii-, ciently smooth to permit the scraper passing evenly over it. It may be in the form of an interiorly heated revolving drum or cylinder the outer face of which forms the drying surface, or it may be a disc, a travelling metallic belt, or other suitably heated smooth surface. 1

The fluid can be applied to the surface by any suitable mechanism. For example, it may be placed ina container positioned above and out of contact with the surface of a revolving cylinder and fed thereto as the latter is revolved in order to spread the liquid evenly in a thin layer on the outer surface thereof, or it can be sprayed on such a surface. In the case of a concentrated pectin liquid the. layer to be dried is preferably about .05 to .06 of an inch in thickness and it adheres to and moves with the drying cylinder, where a cylinderis employed, for a predetermined period suflicient to properly dry the film. The temperature of the drying surface, the period of drying and thethickness of the layer are so coordinated and controlled that the pectin will not be unduly heated or have its temperatureraised sufficiently to cause deterioration of the pectin, but the heatingoperation is so controlled, both as to temperature and time, as to dry the pectin into a coherent film which will be about 10% of the applied coating or, in the example given, about .0045 of an inch thick. It will be found that such a dried film can be removed from the drying surface by a suitable scraper or knife which may be of any desired construction and arrangement capable of maintaining a constant contact across the entire extent of the drying surface during the relative movement between such surface and the scraper. The contact must be sufiiciently close to remove all material so that the surface is left perfectly clean. At the same time the scraper must be of such construction that it will pass smoothly over the surface without cutting into it. A flexible steel blade, the edge of which is pressed against the drying surface, with sufficient pressure to provide the necessary contact across the entire surface, has proved to be entirely satisfactory.

Whatever type of drying surface is employed its temperature should be sumciently high to evaporate the desired amount of moisture from the thin film of material so rapidly as to any destructive effect upon the pectin, other than evaporation of moisture therefrom. The temperature and the time of drying are directly related and must be carefully co-ordinated so that the pectin is removed by the knife as soon as the desired degree of drying is attained. Pectin cannot stand a high degree of heat for any appreciable time and it is therefore important to distribute the material over the drying surface quickly, to dry quickly and to remove quickly and this is accomplished by the present process.

I have successfully produced pectin film by exposing the pectin liquid mixed with glycerine,

for approximately 20 seconds, to the outer face of a cylinder heated internally by steam at 25 pounds pressure resulting in a surface temperature of approximately 214 Fahrenheit; also by exposing the mixture for approximately 7 seconds to a cylinder heated by steamat 35 pounds pressure, giving a surface temperature of approximately 225 Fahrenheit. In the drying operation a certain degree of porosity is imparted to the pectin film on the drying surface by the evaporation of water therefrom, the water vapor and steam formed in the drying process producing some porosity in the dried film.

The material is removed by the blade in the form of a film or very thin sheet and in its removal the material acquires a wavy surface. The film thus formed may be collected in any suitable receptacle as it moves in a eontinuous manner over the blade. The pectin film so formed is satisfactory for many purposes and can be employed without further operation inthe manufacture of jellies, jams and the like. However, the present invention contemplates the elimination of the glycerine or other adherence retarding agent from the pectin film without affecting the advantageous properties thereof, so as to provide in film form a substantially pure pectin of reduced moisture content which --is not only resistant to deterioration but readily dispersable.

The extraneous material, such as the glycerine together with any impurities which may have been allowed to remain until this stage of the process, can be removed by passing the pectin film through a solvent such, for example, as alcohol which is capable of dissolving out the glycerine and dissolving or washing out other impurities from the film without affecting the pectin itself. When alcohol is employed I prefer a 95% solution for this purpose, but it will be apparent that other concentrations of alcohol'may be employed as well as other solvents such as ether and the like. The selection of a solvent will, of course, be limited to those materials which will dissolve the impurities of the pectin film and which will not produce any appreciable swelling of the peetin. The film may be passed through a plurality of such baths if it seems necessary and any solvent which may remain in the film itself can be removed by passing the film over a fiat surface warmed sufficiently to vaporize such solvent as may be left in the film, or it may be passed through an air drier or any preferred form of drying mechanism.

The resulting product is a thin, flexible pectin film partially dried into solid form and having a wavy, irregular surface. When it is folded or otherwise arranged to provide a laminated mass, the porosity of the film and the wavy, irregular surface of each layer provide innumerable chan nels and passages throughout the mass which render it pervious to air and moisture. If, at the time the knife removes the film from the drying sur-, face the film is pulled away from theknife under a light tension, the waviness of the surface of the film will be substantially eliminated and a.

smoother, more paper-like surface provided.

While the foregoing description of the present process refers specifically to the use of glycerine as an adherence retarding agent to render the dried pectin film removable from the drying surface and to alcohol for dissolving the glycerine from the finished film, those skilled in this art will understand the use of the other adherenceretarding agents above mentioned, or theirequivdried pectin film made in accordance with the 7 present invention will keep without deterioration and retain its full strength for long periods if packaged in ordinary moisture proof containers.

At the same time, when it is desired to use the film it will disperse readily in any suitable liquid with which it is to be used. a

The making of a satisfactory jelly depends in part upon the active acidity or hydrogen ion concentration of the jelly mixture. Jelly formation occurs when the hydrogen ion concentration falls within a definite pH range, approximately from a pH of 3.55 to a pH of 2.0. By means of the present invention the desired control of the hydrogen ion concentration of the ultimate jelly forming mixture may be obtained by so controlling the preparation of the pectin film that when this film is added to the other ingredients essential to the manufacture of jelly, the hydrogen ion concentration of the mixture will be adjusted to the desired pH value.

In the commercial manufacture of jelly it is necessary that the hydrogen ion concentration of the jelly forming mixture be insufficient for jelly formation in order to prevent a large batch of jelly from setting or solidifying in the kettle before it can be drawn off into jars or other containers. In making jelly commercially, the manufacturer adds sufiicient acid to each container, after the jelly mixture is drawn off into the containers, to adjust the reaction of the concentrated jelly mixture to a hydrogen ion concentration within the jelly field, namely, to a pH of 3.55 to 2.0. For commercial jelly manufacture as above described, pectin should have a hydrogen ion concentration correspcndingto a pH value above 3.55. If the method of extraction of the pectin from the pectin pomace and the conditions under which this method is carried on are such thatthe reaction of the resulting pectin is below a pH of 3:55, due to excessive acidity, this may beovercome and the pH value may be increased to any desired point by adding a weak alkali to the bath through which the pectin film is passed to remove the extraneous materials. Such componds as sodium acetate, sodium bicarbonate or the like may be used to increase the pH value, preferably to above 3.55. By this process the hydrolytic action of the alkali, which is destructive to the pectin, is much less than when the alkali is added directly to the original pectin solution as has heretofore been the customary practice. Another advantage of the present process results from the fact that the salts formed in the neutralization, the presence of which may lower the jellying power of the pectin, can be readily removed from- 3.0. The present invention comprises steps for the purpose of producing an increase of the hydrogen ion concentration of the pectin if such increase is desirable. If, for example, the reaction of the pectin film is above a pH of 3.55, due to an excessive ash content of the pectin, this may be reduced to any desired value by the addition of a suitable acid to the bath through which the pectin film is passed to remove extraneous material, thus reducing the ash content of the pectin and at the same time increasing its hydrogen ion concentration. A considerable portion of the ash of pectins is due to the alkali and alkaline earth metals in combination with the carboxyl groups of the pectin molecule. The addition of an acid to the pectin forms salts with these metals and the hydrogen ion of the added acid takes the place of metals in the carboxyl groups. The nature of the acid employed is unimportant as long as the acid and its salts are sufficiently soluble in the bath. Hydrochoric acid will be found satisfactory when alcohol is employed as the bath. The resulting pectin film is subsequently washed by passing it through additional baths to remove all free acid and soluble salts therefrom, and the hydrogen ion concentration will be due almost entirely to the carboxyl groups in the pectin molecule.

Thus it will be apparent that the present invention not only provides a new and advantageous method of producing pectin in a novel form but also provides a method of controlling the hydrogen ion concentration of the final pectin product to produce quick setting, slow setting, or any desired rate of setting in the final jelly mixture.

I claim:

1. The method of preparing pectin which comprises applying a liquid pectin having. an adherence retarding agent incorporated therein to a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, and removing said film from said surface.

2. The method of preparing pectin which comprises applying a liquid pectin having an adherence retarding agent incorporated therein to a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, and washing said film with a solvent capable of removing said agent from said film.

3. The method of preparing pectin which comprises applying a liquid pectin having an adherence retarding agent incorporated therein to a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, and treating said film to set the pH value of the pectin within a predetermined range.

4. The method of preparingpectin which comprises mixing an adherence retarding agent in a liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry product, removing the material from said surface, and washing said material in a bath containing an acid to set the pH value of the pectin within a predetermined range.

5. The method of preparing pectin which comprises mixing an adherence retarding agent in a liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer,

subjecting the material on said surface to a dryin'g temperature to form a substantially dry product, removing the material from said surface, and washing said material in a bath containing a weak alkali to set the pH value of the pectin within,

a predetermined range.

6. The method of preparing pectin which comprises mixing an adherence retarding agent in a liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, treating said film to set the pH value of the pectin within a predetermined range, and washing said film in a solvent capable of removing said adherence retarding agent therefrom.

7. The method of producing pectin which comprises mixing glycerine in a pectous liquid, distributing the liquid over a drying surface to form a thin layer thereon, subjecting the material while on said drying surface to a drying temperature to form a substantially dry coherent pectin film having glycerine incorporated therein, and removing said film from said surface.

8. The method of producing pectin which comprises adding an adherence retarding agent to a liquid pectin, forming an emulsion thereof, distributing the emulsion over a drying surface to form a thin layer thereon, subjecting the emulsion while on said surface to a drying temperature to form a substantially dry coherent film, and removing said film from said surface.

9. The method of producing pectin which comprises adding an adherence retarding agent to a liquid pectin, forming an emulsion thereof, distributing the emulsion over a drying surface to form a thin layer thereon, subjecting the emulsion while on said surface to a drying temperature to form a substantially dry coherent film, removing said film from said surface, and washing said' film in a solvent capable of removing said adherence retarding agent from said film.

10. The method of producing pectin which comprises mixing a liquid pectin and an adherence retarding agent obtained from an extraneous source, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry product, and removing the material from said surface.

11. The method of preparing pectin which comprises applying liquid pectin having glycerine incorporated therein to a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, and Washing said film with a solvent capable of removing said glycerine from said film.

12. The method of preparing pectin which comprises applying liquid pectin having glycerine incorporated therein to a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, and treating said film to set the pH value of the pectin within a predetermined range.

13. The method of preparing pectin which comprises mixing glycerine in liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film,

continuously removing said film from said surface, and subjecting said film to the action of a liquid medium containing an acid to set the pH value of the pectin within a predetermined range.

14. The method of preparing pectin which comprises mixing glycerine in liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, and subjecting said film to the action of a liquid medium containing an alkali to set the pH value of the pectin within a predetermined range.

15. The method of preparing pectin which comprises mixing glycerine in liquid pectin, distributing said liquid over a drying surface in the form of a relatively thin layer, subjecting the material on said surface to a drying temperature to form a substantially dry coherent film, continuously removing said film from said surface, continuously subjecting said film to the action of a liquid medium containing an agent adapted to set the pH value of the pectin within a predetermined range, and passing said film through a solvent capable of removing said glycerine therefrom.

16. That step in the method of preparing pectin which consists in forming a continuous unbroken film of partially dried pectin and continuously subjecting said film to the action of a liquid medium containing an agent capable of removing impurities from the film without affecting the pectin.

17. That step in the method of preparing pectin which consists in forming a continuous unbroken film of partially dried pectin and continuously subjecting said film to the action of a liquid medium containing alcohol to remove impurities from the film without affecting the peetin.

18. That step in the method of preparing pectin which comprises forming a. continuous unbroken film of partially dried pectin and continuously and progressivelysubjecting said film to the action of a liquid medium containing an alkali to reduce the hydrogen ion concentration to a predetermined point.

19. That step in the method of preparing pectin which comprises forming a continuous unbroken film of partially dried pectin and progressively and continuously subjecting said film to the action of a liquid medium containing an acid to increase the hydrogen ion concentration of the pectin to a predetermined point.

20. That step in the method of preparing pectin which comprises forming a continuous unbroken film of partially dried pectin and progressively and continuously subjecting said film to the action of a liquid medium containing an agent capable of dissolving extraneous materials from said film without dissolving the pectin and an agent adapted to fix the pH value of the pectin within a predetermined range.

WILLIAM W. COWGILL. 

